RCA TRK-120, without its TV chassis
 

Hi all-

I am now the happy owner of a TRK-120 that was recently discussed on the Antique Radio Forums. Its TV components were removed and replaced with a record player, perhaps as long ago as the 1950s or even late 1940s. The work was quite high quality, and it probably saved the set from being discarded entirely decades ago. The turntable was replaced with a newer one at a later date as well; there are two boards with different cutout patterns for each player.

My intent is to restore/rebuild the cabinet parts that were modified or removed for the conversion, and then likely engineer a way to put a newer RCA TV chassis (probably an 8-T-241/KCS-28) with a 12-inch CRT in place while looking and hoping to eventually find an original chassis set.

Glad that set went to someone who appreciates what it is. Your idea sounds great. A big job for sure, but worth it. It's the most iconic early TV. Good luck!

Great news! I was flipping around the Antique Radio site a couple weeks back and read the story :)

What a fun project!

Not fun. I'm in the throes of a similar thing, though I now have all but the back.

My cabinet had the TV chassis mount hacked but the three holes are there ....
as are some extras in the front that will need to be filled and reveneered.

As the CRT image will be viewed via the mirror, you will need to reverse the two wires to the vertical portion of the deflection yoke. This will make the image on the CRT become mirror image reversed, which will then look correct when viewed thru the lid mirror.
http://videokarma.org/attachment.php...9&d=1432018233

Another thought, possibly heresy :sigh:, would be to use a VGA CRT monitor, again reversing the vertical yoke wires, and using a source like a cable box with a HDMI output port, and a HDMI to VGA converter module (many on that auction site we all love, the automated shopping linker will point you there). But to do this without irreversibly chopping up the cabinet, so you could install the proper chassis if you should get one.

Thank you all for the nice comments. I do know that the "retrofit" will be a bunch of work, and my main goal will be to do it without modifying the cabinet itself (and, first, I also have to get the cabinet back to its original configuration, too).

I already possess the 8-T-241, unrestored and in a poor cabinet, so that is why I picked it. Using another RCA for the replacement seemed to be a good idea to me, too, and I confirmed that its yoke is the same one that was used on a later 12-inch RCA set, the T-120.

Depending on how hard I want to work on this, I will consider moving the components of the 8-T-241 chassis onto a new metal chassis the size/shape of the original TRK-120 chassis, but I do not know if this is even feasible. None of this is going to happen quickly, in any case, so I will take plenty of time to do a decent job of whatever works best.

At least that cabinet was very well kept. Sounds like a fun project.

If you are patient, an original chassis will show up. TRK-12/120s are the most common prewar set, with over 50 survivors. Eventually we will most likely be able to rebuild 12AP4s. Try not to make permanent modifications in the cabinet.

Awrite !! Great story !

Steve, my intent is to not modify the cabinet at all (other than what has already been done, which I want to un-do as much as possible). I figure, the newer chassis and CRT/yoke are probably both smaller enough that I can make adapter brackets to bolt into the existing original nut inserts, remote-mount the raster controls under the proper holes in a replacement control panel, and maybe some type of gear/lever system to control the tuner from knobs/shafts in their proper place on the panel as well. "First, do no harm" is the way to proceed, and I am in no hurry.

Do you know if the silver-gray paint covering the inside of the cabinet is something special (heat-resistant or any other specific properties)? Where it has flaked off a bit, it looks pretty thick.

I just noticed-this is a 50 Hz set, according to the label. I will have to study the schematic diagrams-does that affect the set's operation in any way, I wonder?

The paint is nothing special.

I have never heard of a 50 Hz version. Can you post the label?

Parts of California was 50HZ at the time the set was new.
There's a few articles about it, on the various forums. :scratch2:
50 HZ transformers are fine on 60HZ.
The chance of you getting another 50HZ chassis is rather slim, so it's no concern.

I know that 50 Hz power was used in LA. However, I really doubt if RCA made a 50 Hz version of the TRK-120.

Steve,
Check out the TRK12/120/9/90 schematics in the Red Books. If you look at the power supply sections you'll see they have the main filter cap values (and a few other parts), in both the LV and HV sections, shown with a second value in parenthesis for 50cycle operation. For instance the HV caps are shown .03uF (.1uF 50 cycle) This is also the same on the TRK5/TT5 schematics. I have never seen a set that was actually setup this way, but perhaps this was for the LA market.

There is a section in the manual on the differences between the 50/60 sets. It mostly outlines the capacitor value changes, the transformer changes, the the LV rectifier changing to a 5T4. One very interesting aspect is these sets still ran on 60Hz video so the wobble in the picture when running them on 50Hz mains must have been a problem. They used a metal crt sleeve instead of the cardboard one and a double wall metal sleeve over the yoke. Still I imagine wobble would have been a problem.

Darryl

Thanks Darryl. I learn something new every day.

Steve-

Here is a picture of the label. Thank you for the paint information.

Dieseljeep-

Thank you for the note about 50 Hz power in Los Angeles. That is likely where this set came from. The differences appear to have only been in the TV chassis; the radio main and power supply chassis are the same in both versions of the TRK-120.

Darryl-

Those are interesting comments about the 50 Hz wobble issue.

My set's tube chart has the TRK-120 layout but uses the older tube numbers (1852,1853) rather than 6AB7 and 6AC7.

I was wondering if the TT-5 I purchased recently in Long Beach CA could has been produced for the Los Angeles market but it appears to be 60 Hz by the label. So it most likely was brought in later by someone moving into the area.

I had no idea that Southern California was on 50 Hz power at one point. Just did some reading up on it, and indeed it was -- until 1948. It was a sizeable market, so manufacturers made special versions of all kinds of products specifically for Southern California. Amazing!

Japan today is still cut in half -- 50 Hz in one half, and 60 Hz in the other. When the electric trains cross the boundary, they coast without power a short distance and pick up the new frequency after a few seconds. They should have made the switch like Southern California did long ago.